Patent Document 1 discloses an antenna device capable of reducing production costs and antenna weight. This antenna device includes a dipole antenna disposed forward from a center area of a reflector plate. The reflector plate includes foldover portions on both side portions thereof.
Patent Document 2 discloses an antenna device capable of variably setting a horizontal radiation beam width over a wide range. This antenna device has a structure in which a dielectric layer and a radiating element are stacked upon a ground conductor plate. Furthermore, a reflector is provided at a predetermined distance from the ground conductor plate, on both side portions on a bottom surface of the ground conductor plate.
Patent Document 3 discloses an antenna device having a radiation pattern that is almost nondirectional. In this antenna device, a built-in antenna is attached to a power supply point of a first conductor plate. A second conductor plate is provided on a different side of the first conductor plate from the side on which the built-in antenna is disposed. One side (a ground side) of the second conductor plate is grounded to the first conductor plate.
Patent Document 1: Japanese Unexamined Patent Application Publication No. 2010-245892
Patent Document 2: Japanese Unexamined Patent Application Publication No. 2003-115715
Patent Document 3: Japanese Unexamined Patent Application Publication No. 2007-81712